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|United States Patent
,   et al.
March 13, 2001
Cell cover for electrolytic cells
Anti-corrosive apparatus cover with an improved detachable wall-covering
for new or used covers of electrolytic cells.
Foreign Application Priority Data
Clasen; Peter (Krefeld, DE);
Venghaus; Stefan (Kalkar, DE)
Bayer Aktiengesellschaft (Leverkusen, DE)
June 17, 1999|
January 3, 1998
June 17, 1999
June 17, 1999
|PCT PUB. Date:
July 16, 1998|
|Jan 10, 1997[DE]||197 00 534|
|Current U.S. Class:
||204/279; 204/232; 204/242 |
|Field of Search:
U.S. Patent Documents
|4087343||May., 1978||Custer et al.||204/286.
|4443315||Apr., 1984||Iijima et al.||204/253.
|Foreign Patent Documents|
|23 40 240 B2||Mar., 1975||DE.
|30 08 453 C2||Sep., 1980||DE.
|31 16 193 A1||Feb., 1982||DE.
Primary Examiner: Bell; Bruce F.
Attorney, Agent or Firm: Norris McLaughlin & Marcus
What is claimed is:
1. Apparatus cover with an anti-corrosion lining (2) consisting of a
plastic material and at least one electric current duct (12), wherein the
lining (2) is connected in a fixed and gas-tight manner to the current
duct (12) with a sleeve (5) projecting above the cover wall (1), the
sleeve (5) is secured with a detachable securement means (6) to the cover
wall (1), and the space between the current duct (12) and the sleeve (5)
is sealed by means of a detachable sealant (8), the current duct (12)
being electrically insulated with respect to the sleeve (5) and the cover.
2. Apparatus cover according to claim 1, further comprising an additional
sealant (7) surrounding the sleeve.
3. Apparatus cover according to claim 1 wherein the securement means (6) is
a clamping ring that engages in a groove (13) on the sleeve (5).
4. Apparatus cover according to claim 1, wherein the securement means (6)
is a sleeve nut (16) that engages in a thread (17) on the sleeve (5).
5. Apparatus cover according to claim 1, wherein the sealant (8) surrounds
and electrically insulates the current duct (12) also in the interior (15)
of the sleeve.
6. Apparatus cover according to claim 1, wherein an additional insulation
layer (4) of closed-cell polymer foam.
7. The apparatus cover of claim 6, wherein said foam is a polyurethane
8. Apparatus cover according to claim 1, wherein the underside of the cover
(1) is provided with an additional corrosion protection layer (11).
9. A housing cover for electrolytic cells comprising the apparatus cover of
10. The apparatus cover of claim 1, wherein said plastic material is
selected from the group consisting of polyvinylidene fluoride (PVDF),
polytetrafluoroethylene-co-hexafluoropropylene (FEP), perfluoroalkoxy
polymers (PFA) and polyvinyl chloride (PVC).
The present invention relates to anti-corrosion apparatus covers, in
particular cell covers for electrolytic cells, with an improved wall
covering. The proposed simple detachable covering is particularly suitable
for use in new or used covers of electrolytic cells operating according to
the amalgam process.
BACKGROUND OF THE INVENTION
At least three different methods are known for lining metal electrolytic
cell covers that are suitable for use in the amalgam process:
The application of a non-detachable rubber covering or lining to a
conventional steel cover or internally lining the cover with
non-detachable titanium sheets.
In addition plastics sheets may also be used to cover the cells (so-called
The disadvantage of rubberised covers is that dioxin-containing and
furan-containing reaction products can form on rubberised covers as the
result of reaction with chlorine. A further disadvantage is the
complicated and expensive maintenance of such covers. If a rubberised
cover is to be relined, the rubber covering must first of all be brought
to a state of brittle fracture, for example by subjecting it to cold,
following which the rubber residues adhering to the cover have to be
Titanium-lined cell covers have the following disadvantages. The lining of
steel covers with titanium sheets is fairly complicated and costly on
account of the numerous welds on the anode ducts in the cell cover. Even
if the titanium lining is only slightly damaged moist chlorine can come
into contact with the cell cover, resulting in serious corrosion of the
steel part. A proper skilled repair welding on the titanium lining is not
possible on account of the deficient gas saturation of the gap between the
titanium lining and corroded steel cover.
The replacement of a steel cover by a "membrane cover" of plastic material
is very costly and difficult to implement in practice, since among other
things the construction has to be altered for the current conduction.
Besides, membrane covers have the disadvantage that they restrict the
possibility of adjusting the anodes vertically.
SUMMARY OF THE INVENTION
The object of the invention is to provide an apparatus cover with an
anti-corrosion lining that does not have the disadvantages of the known
constructions, the cover being provided with a readily detachable lining
of plastics material or metal. In particular provision should be made for
current ducts, for example when the cover is used as an electrolytic cell
This object is achieved according to the invention if the ducts for the
anodes are installed, for example by welding, on prepared, i.e. cut to
size, drilled or machined sheets of plastic or metal, in particular of
titanium or titanium alloys. After the lining has been applied to the
steel covers the anode sleeves are prevented from slipping out of the
bores by means of suitable retaining devices, for example retaining sheets
The invention provides an apparatus cover with an anti-corrosion lining and
at least one electric current duct, characterised in that the lining is
joined in a secure and gas-tight manner to the current duct with a sleeve
projecting above the cover wall, that the sleeve is secured by means of a
detachable securement means to the cover wall, and that the space between
the current duct and the sleeve is sealed by means of a detachable
sealant, the current duct being electrically insulated with respect to the
sleeve and the cover.
An additional sealant surrounding the sleeve and that prevents the escape
of corrosive gases is preferably provided on the apparatus cover.
In a special embodiment the securement means for securing the sleeve on the
cover is a clamping ring that engages in a groove on the sleeve, or a
sleeve nut that engages in a thread on the sleeve.
In a further preferred variant the sealant on the current duct extends
sufficiently far down so that it encloses and electrically insulates the
current duct also in the interior of the sleeve.
An additional insulation layer of a closed-cell polymer foam, in particular
a polyurethane foam, is preferably provided, for example in sheet form,
between the lining and the cover wall.
The lining of the cover wall may be of plastics material, in particular
polyvinylidene fluoride (PVDF),
polytetrafluoroethylene-co-hexafluoropropylene (FEP), perfluoroalkoxy
polymers (PFA) or PVC, PVC-HT, or of metal, in particular titanium or its
alloys. The lining is particularly preferably of titanium.
Apart from being lined with metal sheets, e.g. of titanium, cell covers may
as described above also be lined with plastics, for example PVDF, FEP,
PFA, PVC. The large-area sheets of the lining and the sleeves for the
anode ducts may be joined to one another under optimum conditions, for
example by welding. The surface of the metal cell cover may be provided
with an additional coating to prevent corrosion. DD paints or epoxy resins
are particularly suitable as materials for such a coating.
Should the lining be damaged after removal from the cell cover, the lining
can easily be repaired since it is readily detachable from the cell cover.
The structurally influenced gap between the lining and cover also permits
the leak-proofness and tightness of the lining to be checked.
The covers may additionally be provided on all sides with a suitable
coating to prevent corrosion.
Tests with loose plastic linings have shown that, despite the high
coefficient of thermal expansion of the plastic, they are also suitable
for lining covers. If the detachable linings are of metal, all welding
work can be carried out under optimum conditions.
The proposed detachable compounds are particularly suitable for lining
metal covers of electrolytic cells for producing chlorine according to the
The invention also provides the use of the apparatus cover according to the
invention as a housing cover for electrolytic cells, in particular for
chlorine-alkali electrolysis, for example by the amalgam process.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in more detail hereinafter with the aid of the
drawings, without however being restricted thereto as regards details.
FIG. 1 is a side view of an embodiment of the apparatus cover according to
FIG. 2 shows a detail corresponding to a section A-A' in FIG. 1 in the
region of the sleeve 5 and the current duct 12,
FIG. 3 shows an alternative detail corresponding to a section A-A' in FIG.
1 in the region of the sleeve 5.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a segment of a cover of an electrolytic cell in which chlorine
is produced according to the amalgam process, with a loose lining 2 of
plastic and a conventional anode duct 12 through the cover 1. In practice
the sheet-like lining 2, for example of PVDF, FEP, PVC, is connected in a
gas-tight manner, for example by welding, to the sleeve 5 for the anode
duct 12 (see FIG. 2) before installation on the cell cover 1. The cell
cover 1 is then placed on the lining 2, the sleeves 5 extending through
bores 3 in the cover wall 1. An insulation 4 forming a barrier for harmful
gases is in addition provided between the cell cover 1 and lining 2.
FIG. 2 shows a section through a sleeve 5 with an anode duct 12. Split
holding means, for example clamping rings of plastic or metal engaging in
a groove 13 in the sleeve 5, prevent the sleeves 5 slipping out from the
bores 3 in the cover 1. Alternatively, the sleeves can for example also be
prevented from slipping out by a screw connection 16, 17, (see FIG. 3).
The anodes 12 are sealed for example by a rubber washer 8 pressed by means
of the flange 9 and the screw connections 10 against the upper edge of the
sleeve 5, in order for example to seal the reaction space from the
environment. The further seal 7 is intended to prevent moisture
penetrating between the lining 2 and cell cover 1, for example when
cleaning the top of the cover. In order to prevent corrosion on the
underside of the cover 1 the latter is provided with a suitable corrosion
The same construction is also suitable for a lining based on metallic
materials, for example containing titanium.
FIG. 3 shows a section through a sleeve 5 with an anode duct 12, in which
the sleeve is fixed by means of a sleeve nut 17. In this example the
rubber seal is extended downwards in the interior 15 of the sleeve 5 in
order to prevent a short-circuit between the duct 12 and the sleeve 5 when
the latter is made of metal.